<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .gap-10{
            height: 10px;
        }
        .line{
            height: 1px;
            background: black;
        }
        .normal{
            height: 1px;
            background: black;
        }

        @media screen and (-webkit-min-device-pixel-ratio: 2){
            .line{
                transform: scaleY(0.5);
            }
        }

        @media screen and (-webkit-min-device-pixel-ratio: 3){
            .line{
                transform: scaleY(0.33333);
            }
        }

        .test{
            width: 280px;
            height: 100px;
            position:relative;
        }

        /* 伪元素 */
        .test::after{
            content: '';
            width: 100%;
            height: 1px;
            background: black;
            position:absolute;
            left: 0;
            bottom: 0;
        }

        @media screen and (-webkit-min-device-pixel-ratio: 2){
            .test::after{
                transform: scaleY(0.5);
            }
        }

        @media screen and (-webkit-min-device-pixel-ratio: 3){
            .test::after{
                transform: scaleY(0.33333);
            }
        }

    </style>
</head>
<body>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <h2>分割线</h2>
    <div class="normal"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="gap-10"></div>
    <div class="line"></div>

    <h2>边框</h2>

    <div class="test"></div>


</body>
</html>